Issue #4965 has been updated by mame (Yusuke Endoh).

Status changed from Open to Assigned
Assignee set to matz (Yukihiro Matsumoto)


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Feature #4965: The problem of "print line if line = DATA.gets"
https://bugs.ruby-lang.org/issues/4965#change-25144

Author: yimutang (Joey Zhou)
Status: Assigned
Priority: Normal
Assignee: matz (Yukihiro Matsumoto)
Category: 
Target version: 


Right now, I find the following code will raise an exception:

print line if line = DATA.gets 
__END__
abcdef

# undefined local variable or method `line' for main:Object (NameError)

"print line while line = DATA.gets" also doesn't work, maybe "unless" "until" modifiers either. 

It seems that the Ruby interpreter is too impatient, once seeing unassigned variable "line", it croaks.

However, the expression after "if" or "while" modifier should be evaluated first. Logically, I think the code above should work properly, there's no need to write "line = nil" before it.


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